Visualizing a view of a scene

ABSTRACT

A system for visualizing a view ( 1 ) of a scene ( 2 ) comprising a three- dimensional image and an object ( 3 ) is provided. View parameter establishing means ( 5 ) are arranged for establishing a first view parameter value based on a first object parameter value. View visualization means ( 6 ) are arranged for visualizing the view ( 1 ) of the image in accordance with the first view parameter value. Interaction means ( 7 ) are arranged for enabling a user ( 9 ) to indicate a point ( 12 ) in the view ( 1 ). Object parameter updating means ( 8 ) are arranged for updating the object parameter ( 11 ) based on the point ( 12 ) to obtain a second object parameter value. The view parameter establishing means ( 5 ) is arranged for updating the view parameter ( 10 ) based on the second object parameter value to obtain a second view parameter value. The view visualization means ( 6 ) is arranged for sequentially visualizing at least one view of the image in accordance with an intermediate view parameter value between the first view parameter value and the second view parameter value, and a view ( 13 ) of the image in accordance with the second view parameter value.

FIELD OF THE INVENTION

The invention relates to visualizing a view of a scene comprising athree-dimensional image and an object, the view having a view parameterassociated therewith, the object having an object parameter associatedtherewith. The invention also relates to medical image analysis, moreparticularly vessel analysis.

BACKGROUND OF THE INVENTION

Tools for three-dimensional visualization of three-dimensional (3D)datasets are known. In the medical field, such tools are used to supportvessel analysis. These tools may offer functionality for advancedviewing, segmentation, inspection and quantification of vessels. Thevessel analysis provided by such tools may support inspection of vesselsby means of vessel segmentation. Some vessel analysis toolsautomatically track parts of a vessel structure.

WO 2008/149274 discloses a method of inspecting tubularly shapedstructures (1′) within a three-dimensional (3D) image data set, e.g. avessel in a medical image.

Initially, there is provided an image data set and there is performed avisualization of the image data set. Then, an inspection of the imagedata set is performed. During the inspection the user moves a pointer(P), e.g. via a computer mouse, and a processor performs a localsegmentation around the pointer so as to determine a possible shape of atubularly shaped segmented object (1′), e.g. a vessel, and the processoralso makes a local analysis of the segmented object. Thereafter, ascreen displays a view (P1) of the segmented object (1′), where theorientation of the first view is derived from the local analysis; thefirst view can for example be a cross-sectional or longitudinal view.

The placement of an object over a particular vessel, for example a ringwhich is placed around the vessel, may be used in such a method fordisplaying one or more views aligned with the vessel, for example across sectional view of the vessel or a longitudinal sectional view ofthe vessel, with the vessel and object centered in the view. If theobject is moved with respect to the volume, the sectional views areautomatically updated to re-center around the new position of theobject. However, the manipulation of such a view with an object may bedifficult.

SUMMARY OF THE INVENTION

It would be advantageous to have an improved system for visualizing aview of a scene comprising a three-dimensional image and an object. Tobetter address this concern, in a first aspect of the invention a systemis presented in which the view has a view parameter associatedtherewith, and in which the object has an object parameter associatedtherewith. The system may comprise

-   -   view parameter establishing means for establishing a first view        parameter value based on a first object parameter value;    -   view visualization means for visualizing the view of the image        in accordance with the first view parameter value;    -   interaction means for enabling a user to indicate a point in the        view; and    -   object parameter updating means for updating the object        parameter based on the point to obtain a second object parameter        value;    -   the view parameter establishing means being arranged for        updating the view parameter based on the second object parameter        value to obtain a second view parameter value;    -   the view visualization means being arranged for sequentially        visualizing at least one view of the image in accordance with an        intermediate view parameter value between the first view        parameter value and the second view parameter value, and a view        of the image in accordance with the second view parameter value.

The first view in accordance with the first view parameter valuecorresponds to the first object parameter value, whereas the second viewin accordance with the second view parameter value corresponds to thesecond object parameter value. Jumping from the first view directly tothe second view may be confusing for a user. It may be difficult tounderstand immediately the relationship between the two views, becausethe two views have been created using a different view parameter value.The sequential visualization of the intermediate view may provide for asmoother transition from the first view to the second view. It may allowthe user to better understand the interaction between the objectparameter and the view parameter. Consequently, the user can moreefficiently manipulate the view parameter value. This can be used forefficiently creating a desirable view of the image.

The view visualization means may be arranged for sequentiallyvisualizing views in accordance with a plurality of sequentialintermediate view parameter values. This makes the transition smoother.When a sufficiently large number of views are visualized sequentially,an animation from the first view to the second view may be realized.

The object parameter may comprise a position of the object and/or anorientation of the object. The position of the object may, for example,indicate the desired center of the view, and the orientation of theobject may indicate a desired viewing direction of the view. Theposition and/or orientation of the object may be aligned with a vessel,either manually or automatically, based on the point input. Theindication of the point in the view may be realized by moving theobject, for example using cursor keys.

The view parameter may comprise a geometric parameter of the view. Sucha geometric parameter may include a viewing direction, a zoom factor, acamera position. The geometric parameter may include a position and/ororientation of a plane used in a multi-planar reformat. A geometric viewparameter may be used to define a portion of the image which isvisualized in the view.

The interaction means may be arranged for enabling a user to indicatethe point by means of a mouse pointer. A mouse pointer is a convenientway to indicate a point. For example, the point may be used tore-position the object at the point. For example, the object may bealigned with a vessel visible at the point.

The interaction means may be arranged for enabling the user to indicatea sequence of points, the visualization means being arranged forperforming the sequential visualization upon depressing or releasing abutton. When a sequence of points is traversed, it may be more intuitiveto keep the view parameter value fixed until the end of the sequence isreached.

The interaction means may be arranged for enabling a user to indicatethe sequence of points by dragging the object, the visualization meansbeing arranged for visualizing the object in accordance with a sequenceof object parameters corresponding to the sequence of points, the objectbeing visualized using the first view parameter value. By keeping theview parameter value fixed during the drag operation, the object may beupdated intuitively and visualized in the original view. Only when thedrag operation is completed, the view is re-centered via the sequence ofviews. If the view parameter were updated during the drag operation, itwould be difficult for the user to keep track of the image and theobject.

The visualization means may be arranged for updating the view parameterto avoid the object being moved beyond a border of the view. Should theobject, due to changes in the object parameter, move beyond the borderof the view, out of sight, it is useful to update the view parametersuch that the object becomes visible again in the view.

The image may comprise a volumetric image and the view may comprise amulti-planar reformat of the volumetric image. Such a multi-planarreformat may be useful in many clinical applications. However, asnavigating the image by means of such reformats may be relativelydifficult, it may be especially useful to apply the techniques describedherein to a view comprising a multi-planar reformat.

The volumetric image may represent a vascular structure, and the objectparameter establishing means may be arranged for establishing an objectparameter value corresponding to a position on and/or orientation of avessel portion of the vascular structure indicated by the point. Thetechniques described herein may be advantageously applied to interactiveanalysis of a vascular structure, because such analysis involves manydifferent viewing orientations corresponding to the local vesselorientations.

The view parameter establishing means may be arranged for establishing aview parameter value corresponding to a predetermined position or apredetermined orientation of the object in the view. Suchre-positioning, e.g. re-centering, can be a cause for loosing track ofwhich portion of the image is being visualized. Consequently, theintermediate views are particularly suitable to be applied to such aview parameter.

The visualization means may be arranged for establishing the first andsecond view parameter such that the object appears in the view at apredetermined position and/or orientation with respect to the view.

A method of visualizing a view of a scene comprising a three-dimensionalimage and an object is presented, the object having an object parameterassociated therewith, the view having a view parameter associatedtherewith. The method may comprise:

-   -   establishing a first view parameter value based on a first        object parameter value;    -   visualizing the view of the image in accordance with the first        view parameter value;    -   enabling a user to indicate a point in the view;    -   updating the object parameter based on the point to obtain a        second object parameter value;    -   updating the view parameter based on the second object parameter        value to obtain a second view parameter value; and    -   sequentially visualizing at least one view of the image in        accordance with an intermediate view parameter value between the        first view parameter value and the second view parameter value,        and a view of the image in accordance with the second view        parameter value.

A computer program product may comprise instructions for causing aprocessor system to perform the method set forth.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be further elucidated anddescribed with reference to the drawing, in which

FIG. 1 is a block diagram of a system for visualizing a view of a scene;

FIG. 2 is a block diagram of a method of visualizing a view of a scene;

FIG. 3 illustrates a vessel portion and two positions of a ring;

FIG. 4 illustrates a sketch of a sequence of views after a dragoperation.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following, several embodiments will be described in detail. Theseembodiments are examples only. The skilled person will appreciate thatvariations of the described embodiments are possible within the scope ofthe claims.

A system for visualizing a view 1 of a scene 2 is presented. The scene 2may comprise a three-dimensional image and an object 3. The view 1 maycomprise a portion of the image, for example a vessel portion 4represented by the image. The view has a view parameter 10 associatedtherewith, whereas the object 3 has an object parameter 11 associatedtherewith.

The system may comprise view parameter establishing means 5 forestablishing a first view parameter value based on a first objectparameter value. The system may further comprise view visualizationmeans 6 for visualizing the view 1 of the image in accordance with thefirst view parameter value. The system may further comprise interactionmeans 7 for enabling a user to indicate a point 12 in the view, forexample by means of a trackball, mouse pointer, cursor keys, or touchscreen. Preferably, the point is a point within a viewport in which theview is displayed.

The system may further comprise object parameter updating means 8 forupdating the object parameter 11 based on the point 12 to obtain asecond object parameter value. This second object parameter value can beused to replace the first object parameter value. In this respect, theview parameter establishing means 5 may comprise means for updating theview parameter 10 based on the second object parameter value to obtain asecond view parameter value. Moreover, the view visualization means 6may comprise means for visualizing a view 13 of the image in accordancewith the second view parameter value. The view visualization means 6 mayfurther comprise means for sequentially visualizing at least one view ofthe image in accordance with an intermediate view parameter valuebetween the first view parameter value and the second view parametervalue. This latter at least one view of the image may be visualizedbefore visualizing the view of the image in accordance with the secondview parameter value.

The view visualization means 6 may be arranged for sequentiallyvisualizing a sequence of views corresponding to a sequence ofintermediate view parameter values.

The view or views corresponding to the intermediate view parameter valueor values is referred to hereinafter as intermediate view or views. Thisintermediate view or these intermediate views may be generated, forexample, using a key frame interpolation algorithm. The interpolationalgorithm may be provided with first and second locations and/ororientations of the object corresponding to the first object parametervalue and the second parameter value, respectively. Also, an animationspeed or total animation time may be provided, to prescribe the amountof time during which the intermediate views are displayed. Hermiteinterpolation may be used by employing a formula s=H(t), to compute theintermediate location(s) and/or orientation(s) of the object; fromthese, the intermediate view parameter value(s) may be derived. Hermiteinterpolation is known per se in the art. The two quantities, locationand orientation, may be interpolated independently and combinedafterwards. In the case of a plurality of intermediate views, in apreferred embodiment, the first intermediate views only change thelocation, and after that the orientation starts to change. This improvesthe perceived smoothness of the animation. Instead of, or in additionto, Hermite interpolation, it is possible to use the intermediatepositions of the object obtained during a drag operation, to obtain theintermediate view parameters. Alternatively, the vessel may be trackedalong a centerline of the vessel towards the new position of the object.

The object parameter 11 may define a position of the object and/or anorientation of the object. Consequently, the object parameter updatingmeans 8 may be arranged for establishing a new position and/ororientation of the object based on the point 12. The view parameter 10may comprise a geometric parameter of the view 1. Such a geometricparameter can define a multi-planar reformat of the image, or a frustum,or a viewing direction, or a camera position, for example.

FIG. 3 illustrates a portion of a vessel structure 31 represented by athree-dimensional image, a sequence of points 30, as well as an object 3in accordance with a first object parameter value, and the object 14 inaccordance with a second object parameter value. The interaction means 7may be arranged for enabling the user to indicate such a sequence ofpoints 30, for example by dragging the object 4 around. Such draggingmay be controlled using a mouse device or trackball or touch screen, forexample. Alternatively, it is possible to move the object 4 around insteps using cursor keys or a joystick, for example. The visualizationmeans 6 may be arranged for performing the sequential visualization upondepressing or releasing a button, e.g. a mouse button. More generally,the sequential visualization may start when an indication is receivedthat the sequence of points has ended. For example, after a time delayduring which no new point has been indicated. Until the sequentialvisualization is activated by said indication, the view parameter 10 isnot updated. However, the object parameter 11 may be updated after everypoint in the sequence 30.

The interaction means 7 may comprise means for enabling a user toindicate the sequence of points 30 by dragging the object 3. Moreover,the visualization means 6 may comprise means for visualizing the object3 in accordance with a sequence of object parameters corresponding tothe sequence of points, the object being visualized using the first viewparameter value. In other words, the object 3 is visualized sequentiallyin accordance with a sequence of points 30, while the view parameter 10is not changed. However, the view may be defined by more than just theview parameter 10. Other view parameters may be updated to account forthe changed object parameter 11. For example, a depth of a multi-planarreformat may be updated to account for the changed object parameter 11,whereas the panning of the multi-planar reformat may be defined by theview parameter 10, and kept constant until the end of the sequence hasbeen reached.

The visualization means 7 may be arranged for updating the viewparameter 10 to avoid the object 3 being moved beyond a border 15 of theview 1. Consequently, the object remains visible inside the view. Theview parameter 10 may be updated such that the object 3 is kept near theborder 15 of the view 1, or alternatively the view parameter 10 may beupdated such that the object 3 returns to a predetermined position (e.g.the center) in the view.

As mentioned before, the volumetric image may represent a vascularstructure. The object parameter establishing means 8 may comprise meansfor establishing an object parameter value corresponding to a positionon and/or orientation of a vessel portion of the vascular structureindicated by the point. Such means are known from WO 2008/149274.

The view parameter establishing means 5 may comprise means forestablishing a view parameter value corresponding to a predeterminedposition or a predetermined orientation of the object in the view. Forexample, the object may be centered in the view. The orientation may befrontal or from the side. For example, it is possible to visualize threeviews of the scene 2, as seen from three orthogonal directions. When apoint or a sequence of points is indicated in one of the views, theintermediate view or views are visualized in that one of the views. Theother views may either be updated instantaneously, or may also showintermediate view or views.

FIG. 2 illustrates a method of visualizing a view 1 of a scene 2comprising a three-dimensional image and an object 3, the object 3having an object parameter associated therewith, the view 2 having aview parameter associated therewith. In step 21, a first view parametervalue is established based on a first object parameter value. In step22, the view of the image is visualized in accordance with the firstview parameter value. In step 23, a user is enabled to indicate a pointin the view. In step 24, the object parameter is updated based on thepoint to obtain a second object parameter value. In step 25, the viewparameter is updated based on the second object parameter value toobtain a second view parameter value. In step 26, at least one view ofthe image is visualized in accordance with an intermediate viewparameter value between the first view parameter value and the secondview parameter value. After that, a view of the image is visualized inaccordance with the second view parameter value. The method may beimplemented as a computer program.

FIG. 4 illustrates an example usage of the system of FIG. 1 and themethod of FIG. 2. FIG. 4 diagrammatically shows views 41, 42, 47, 48,49, and 44. View 41 comprises a vessel segment 43 with an object 45. Theobject 45 in this case comprises two arrow shapes on the left and on theright of the vessel segment 43, respectively. The user, via his inputdevice such as a mouse, drags the object 45 to a higher position 46.This is indicated in view 42. In view 42, the vessel 43 is displayed inthe same way as in view 41. When the user stops the drag operation (forexample, by releasing a mouse button), an animation is displayed. Thisanimation comprises the sequential views 47, 48, and 49. The view isgradually changed such that the object 46 is again centered in the view,and the vessel segment displayed gradually becomes the vessel segmentaround the new position of the object 46. Finally, the view 44 isdisplayed. In this view, the object 46 is centered in the view, and thevessel segment around the object 46 is shown.

The view parameter 10 and/or object parameter 11 are not limited togeometric parameters. The parameters could also be used to define acolor map, for example.

In vascular applications, vessels may be visualized for example usingMIPs, surface renderings, volume renderings, curved planar reformats orstraightened reformat views. Moreover, local vessel properties, such asarea and radius, may be measured at several locations in the image datato quantify for example the degree of stenosis or the size of ananeurysm. For the curved planar or straightened reformat visualizationtechniques a path through the vessel center may be used.

Local vessel inspection may be facilitated by using an object, forexample a ring, in the image. Although in the following, a ring is usedas an example of an object, it will be understood that any other kind ofobject (e.g. a square, a plane, a dot) could be used to replace thering.

The ring can be used to align one or more views of an image representinga structure of interest, such that the ring appears at a predefinedposition and orientation in the view. In evaluation it was found thatusers would like to ‘interact’ with such a ring, for example to move thering with respect to the image, which would cause a re-alignment of theview to bring the ring back to the predefined position and orientation.However, if the view is updated while the ring is being interacted with,the ring would remain in a fixed position and orientation in the view;only the visualized portion of the image would change. This was notconsidered intuitive.

During the interaction with the ring, local vessel analysis alignmenttools may be active and update any views as expected (maintaining thevessel alignment). Also the view on which the interaction takes placemay follow the depth of the selected vessel during the interaction. Thering can also be dragged from one vessel into another, so it is notnecessary to always follow a single vessel. A variant on this approachmay keep the ring aligned with the same vessel always, restricting theflexibility a bit but making it easier to follow the vessel.

After interaction with the ring, the view may be re-centered and/orre-orientated with the ring. For example, a multi-planar reformat viewmay be kept parallel to the vessel direction and centered on the ring.When the ring is moved by a user, this automatic realignment may lead toa confusing user interaction. Keeping the view centered around the ringwould lead to a confusing user experience, as the ring which is beingdragged does not appear to move in the view, and instead the whole viewmoves. A solution is to not completely re-align the view around the ringduring drag of the ring—but only when the drag operation is completed.Still, this may in some cases confuse the user because of theinstantaneous re-centering of the view (which might cause the user tolose the overview).

A smooth re-centering may be applied. Such re-centering may use a keyframe interpolation technique to animate the view from the view positionat mouse release to a view position where the ring is centered. Insteadof a ‘jumping view’ the user clearly sees what is going on.

Such animated transitions may be triggered, for example, by any of thefollowing events:

-   -   A click in a view to define a new object position. In such a        case, the animation may be triggered by mouse click.    -   A drag in a view to drag the object to a new position. In such a        case, the animation may be triggered by mouse release.    -   A rotation of the object, e.g. by dragging a corner of the        object. In such a case, the animation may be triggered by mouse        release.    -   A drag of the object beyond the border of the view. In such as        case, the animation may be triggered by the fact that the object        is dragged beyond the border of the view.

Apart from re-centering, the view may also be reoriented parallel to thevessel at that position. Interactive reorientation or rotation of thering may be allowed for correcting mistakes in the auto-alignment of thering. When the ring orientation is altered by (mouse) interaction, theview may be animated to align with the new orientation.

If the user has found a position (using the ring) and wants to do ameasurement, the user can perform a measurement of the vessel at thering position. For example, the lumen, dilatation or length of a portionof a vessel may be measured at the position of the ring. In the case ofa dual ring measurement (such as a length measurement of a vesselportion from a first ring to a second ring), a next click may positionthe second ring, so that the measurement may be completed. Ringsbelonging to a measurement can be edited similarly to the editing of thelive inspection ring. The new ring-based measurements all may haveclearly visible and editable 3D labels to support easy generation ofsecondary capture images for use in a report.

It will be appreciated that the invention also extends to computerprograms, particularly computer programs on or in a carrier, adapted forputting the invention into practice. The program may be in the form of asource code, an object code, a code intermediate source and object codesuch as partially compiled form, or in any other form suitable for usein the implementation of the method according to the invention. It willalso be appreciated that such a program may have many differentarchitectural designs. For example, a program code implementing thefunctionality of the method or system according to the invention may besubdivided into one or more subroutines. Many different ways todistribute the functionality among these subroutines will be apparent tothe skilled person. The subroutines may be stored together in oneexecutable file to form a self-contained program. Such an executablefile may comprise computer executable instructions, for exampleprocessor instructions and/or interpreter instructions (e.g. Javainterpreter instructions). Alternatively, one or more or all of thesubroutines may be stored in at least one external library file andlinked with a main program either statically or dynamically, e.g. atrun-time. The main program contains at least one call to at least one ofthe subroutines. Also, the subroutines may comprise function calls toeach other. An embodiment relating to a computer program productcomprises computer executable instructions corresponding to each of theprocessing steps of at least one of the methods set forth. Theseinstructions may be subdivided into subroutines and/or stored in one ormore files that may be linked statically or dynamically. Anotherembodiment relating to a computer program product comprises computerexecutable instructions corresponding to each of the means of at leastone of the systems and/or products set forth. These instructions may besubdivided into subroutines and/or stored in one or more files that maybe linked statically or dynamically.

The carrier of a computer program may be any entity or device capable ofcarrying the program. For example, the carrier may include a storagemedium, such as a ROM, for example a CD ROM or a semiconductor ROM, or amagnetic recording medium, for example a floppy disc or hard disk.Further, the carrier may be a transmissible carrier such as anelectrical or optical signal, which may be conveyed via electrical oroptical cable or by radio or other means. When the program is embodiedin such a signal, the carrier may be constituted by such a cable orother device or means. Alternatively, the carrier may be an integratedcircuit in which the program is embedded, the integrated circuit beingadapted for performing, or for use in the performance of, the relevantmethod.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention, and that those skilled in the art willbe able to design many alternative embodiments without departing fromthe scope of the appended claims. In the claims, any reference signsplaced between parentheses shall not be construed as limiting the claim.Use of the verb “comprise” and its conjugations does not exclude thepresence of elements or steps other than those stated in a claim. Thearticle “a” or “an” preceding an element does not exclude the presenceof a plurality of such elements. The invention may be implemented bymeans of hardware comprising several distinct elements, and by means ofa suitably programmed computer. In the device claim enumerating severalmeans, several of these means may be embodied by one and the same itemof hardware. The mere fact that certain measures are recited in mutuallydifferent dependent claims does not indicate that a combination of thesemeasures cannot be used to advantage.

1. A system for visualizing a view (1) of a scene (2) comprising athree-dimensional image and an object (3), the view (1) having a viewparameter (10) associated therewith, the object (3) having an objectparameter (11) associated therewith, comprising view parameterestablishing means (5) for establishing a first view parameter valuebased on a first object parameter value; view visualization means (6)for visualizing the view (1) of the image in accordance with the firstview parameter value; interaction means (7) for enabling a user (9) toindicate a point (12) in the view (1); and object parameter updatingmeans (8) for updating the object parameter (11) based on the point (12)to obtain a second object parameter value; the view parameterestablishing means (5) being arranged for updating the view parameter(10) based on the second object parameter value to obtain a second viewparameter value; the view visualization means (6) being arranged forsequentially visualizing at least one view of the image in accordancewith an intermediate view parameter value between the first viewparameter value and the second view parameter value, and a view (13) ofthe image in accordance with the second view parameter value.
 2. Thesystem according to claim 1, the view visualization means being arrangedfor sequentially visualizing views in accordance with a plurality ofsequential intermediate view parameter values.
 3. The system accordingto claim 1, the object parameter comprising at least one of: a positionof the object, an orientation of the object.
 4. The system according toclaim 1, the view parameter comprising a geometric parameter of theview.
 5. The system according to claim 1, the interaction means beingarranged for enabling a user to indicate the point by means of a mousepointer.
 6. The system according to claim 1, the interaction means beingarranged for enabling the user to indicate a sequence of points, thevisualization means being arranged for performing the sequentialvisualization when an indication is received that the sequence of pointshas ended.
 7. The system according to claim 6, the interaction meansbeing arranged for enabling a user to indicate the sequence of points bydragging the object, the visualization means being arranged forvisualizing the object in accordance with a sequence of objectparameters corresponding to the sequence of points, the object beingvisualized using the first view parameter value.
 8. The system accordingto claim 6, wherein the visualization means is arranged for updating theview parameter to avoid the object being moved beyond a border of theview.
 9. The system according to claim 1, the view comprising amulti-planar reformat of the volumetric image.
 10. The system accordingto claim 9, the volumetric image representing a vascular structure, andthe object parameter establishing means being arranged for establishingan object parameter value corresponding to a position on and/ororientation of a vessel portion of the vascular structure indicated bythe point.
 11. The system according to claim 9, the view parameterestablishing means being arranged for establishing a view parametervalue corresponding to a predetermined position or a predeterminedorientation of the object in the view.
 12. A method of visualizing aview of a scene comprising a three-dimensional image and an object, theobject having an object parameter associated therewith, the view havinga view parameter associated therewith, comprising establishing a firstview parameter value based on a first object parameter value;visualizing the view of the image in accordance with the first viewparameter value; enabling a user to indicate a point in the view;updating the object parameter based on the point to obtain a secondobject parameter value; updating the view parameter based on the secondobject parameter value to obtain a second view parameter value; andsequentially visualizing at least one view of the image in accordancewith an intermediate view parameter value between the first viewparameter value and the second view parameter value, and a view of theimage in accordance with the second view parameter value.
 13. A computerprogram product comprising instructions for causing a processor systemto perform the method according to claim 12.